About the worst I have ever done was when I was 15. I was riding a bike trail that ended abruptly at a busy road. Not wanting to ride on the busy road I hurried across, fully expecting there to be a curb cut on the other side leading up to the sidewalk. (At that time I didn't know that I was supposed to be on the road.)

So I sped across the road, watching for traffic each way, not looking for the curb cut. There was no curb cut. I pulled a very nice endo in front of the driver's ed class that was exiting the high school; 50-100 15yo's who got a good laugh out of my spill.

I was pretty banged up too. Road rash on hands, elbows, and knees. Blood running into my shoes. There were however some people nice enough to stop and see if I was okay. I got quite a few looks riding back through town though... I was a bloody mess.